Kemmler Slim Hydraulic Expansion Chucks

Available Sizes and Part Numbers

Purpose and Application

Kemmler Hydro Slim series hydraulic expansion chucks are designed for installation on CNC milling machines and machining centers with SK 40 spindles according to ISO 7388-1 (formerly DIN 69871). The specially optimized slim body geometry (Slim design) is developed for toolmaking and mould making, where machining deep grooves and cavities with reduced interference contour is required.

Design and Features

The chuck operation is based on a closed hydraulic system. Tool clamping is performed by tightening a screw with a hex wrench, creating high internal oil pressure that uniformly compresses the clamping sleeve around the shank. The thin-walled extended front section with projection LPR = 160 mm freely accesses deep workpiece cavities. The hydraulic fluid acts as a damper, effectively absorbing micro-vibrations, enhancing surface finish quality, and extending cutting edge tool life. Inner taper radial runout is ≤ 3 µm, and factory balancing is executed to class G 2.5 at 25,000 rpm. An RFID chip bore is provided in the body.

Compatibility

The chucks are compatible with machine spindles featuring SK 40 tapers (ISO 7388-1 / DIN 69871). Designed for clamping tools with cylindrical shanks conforming to DIN 1835 Form A, B, E and DIN 6535 Form HA, HB, HE (with h6 shank tolerance). Precision reduction sleeves can be used to clamp smaller diameter shanks. Spindle retention is achieved using pull studs according to ISO 7388-3 (formerly DIN 69872).

Selection Parameters

Selection is based on tool bore diameter (6, 8, 10, 12 mm) with a standard extended projection LPR = 160 mm. Coolant supply is implemented in Form AD/B execution (universal supply through center or flange).

Key Advantages

• Reduced Interference Contour: slim and extended geometry allows operation in deep mold cavities without collision risk.
• Vibration Damping: closed hydraulic system absorbs vibration oscillations, improving surface finish and milling cutter life.
• Precision Accuracy: radial runout ≤ 3 µm guarantees accurate part dimensions.
• High-Speed Balancing: class G 2.5 at 25,000 rpm ensures stable machining at high spindle speeds.
• Speed and Convenience: fast tool changes using a single hex wrench without special heating equipment.